Prosecutors said each man is employed by Fayette Regional Health System based in Connersville, about 50 miles east of Indianapolis. A message seeking comment was left with hospital administrators.
"Overprescribing of powerful opiate painkillers across our state has contributed in part to the epidemic of prescription drug abuse in Indiana and fueled addiction at the expense of patients' safety and health," Attorney General Greg Zoeller said in a news release announcing the arrests.
Ferryman, 50, faces seven counts of dealing in narcotics and seven counts of forgery. Palmer, 56, faces eight counts of conspiracy to deal in narcotics, 10 counts of conspiracy to commit forgery, and two counts of conspiracy to deal in a controlled substance. Ringel, 54, faces four counts each of conspiring to deal in a controlled substance and conspiracy to commit forgery.
All three men were being held in the Fayette County Jail without bond. It wasn't clear whether they had attorneys.
The arrests Thursday followed the October arrest of physician assistant David Wulff. Zoeller said Wulff is awaiting trial on charges of dealing in narcotics and controlled substances, forgery and acquiring controlled substances by fraud. A message seeking comment was left for Wulff's attorney.
The Connersville News-Examiner reported an August search by federal, state and local authorities of Wulff's office in the Fayette Regional Health Primary Care clinic turned up three blank prescription pads — numbering 50 prescriptions each — bearing Ringel's signature.
The same search turned up two blank prescription pads — each containing 50 prescriptions each — along with a partial blank prescription pad, all pre-signed by Palmer, the newspaper reported
Palmer was Wulff's supervising physician in April 2013, when he allegedly pre-signed prescriptions that Wulff used to prescribe the painkiller Oxycodone and the stimulant Adderall, used to treat attention deficit disorder.
An affidavit said Palmer also pre-signed prescriptions for Ferryman. The affidavit said a primary care clinic doctor and office manager told authorities that hospital administrators asked doctors to sign blank prescription pads for use by physician's assistants.
Randy White, Fayette Regional Health's chief executive officer, has said its doctors and employees follow state law in prescribing medications.